KR20060061849A - Fluid bearing device - Google Patents

Abstract

A fluid bearing device, wherein the outer peripheral surface (8d) of a bearing sleeve (8) is press-fitted with a specified interference into the inner peripheral surface (7c) of a housing (7) and fused to each other while applying ultrasonic vibration to the housing (7) or/and the bearing sleeve (8). Since the area of the inner peripheral surface (7c) of the housing (7) which comes into contact with the bearing sleeve (8) is fused or softened by the action of the ultrasonic vibration in the press-fitting, a press-fitting force in the press-fitting can be remarkably reduced less than that in a case where press-fitting only is performed.

Description

Fluid Bearing Device {FLUID BEARING DEVICE}

The present invention relates to a fluid bearing device for non-contacting support of a rotating member by an oil film of lubricating oil generated in a radial bearing gap. The bearing device of the present invention is an information device such as a magnetic disk device such as HDD, FDD, optical disk device such as CD-ROM, CD-R / RW, DVD-ROM / RAM, magneto-optical disk device such as MD, MO Spindle motors, polygon scanner motors of laser beam printers (LBPs), or small motors such as electric machines such as axial fans.

In addition to the high speed rotation accuracy, the various motors are required to have high speed, low cost, low noise, and the like. One of the components that determine these required performances is a bearing for supporting the spindle of the motor, and recently, as a bearing of this kind, the use of a fluid bearing having characteristics excellent in the required performance has been examined or actually used. .

These types of fluid bearings are roughly divided into dynamic bearings having dynamic pressure generating means for generating dynamic pressure in the lubricating oil in the bearing gap, and so-called cylindrical bearings (bearings having a rounded bearing surface) which are not provided with dynamic pressure generating means. Lose.

For example, in a fluid bearing device which is assembled to a spindle motor of a disk device such as an HDD, a radial bearing portion for rotatably supporting a shaft member in a radial direction and a thrust bearing rotatably supporting a shaft member in a thrust direction are provided. As the radial bearing portion, a hydrodynamic bearing having a dynamic pressure generating groove (dynamic pressure groove) formed on the inner circumferential surface of the bearing sleeve or the outer circumferential surface of the shaft member is used as the radial bearing portion. As the thrust bearing portion, for example, a hydrodynamic bearing having a dynamic pressure groove formed on both end surfaces of the flange portion of the shaft member or on a surface opposed thereto (the end surface of the bearing sleeve or the end surface of the thrust member fixed to the housing) is used. (For example, refer patent document 1). Or as a thrust bearing part, the bearing (so-called pivot bearing) of the structure which contacts and supports one end surface of a shaft member with a thrust plate may be used (for example, refer patent document 2).

Usually, in order to prevent the bearing sleeve from being fixed to a predetermined position on the inner circumference of the housing, and to prevent leakage of the lubricating oil lubricated in the inner space of the housing to the outside, the sealing member is often disposed in the opening of the housing.

Patent Document 1: Japanese Patent Application Laid-Open No. 2000-291648

Patent Document 2: Japanese Patent Application Laid-Open No. 11-191943

The fluid bearing device having the above-described configuration is composed of components such as a housing, a bearing sleeve, a shaft member, a thrust member, and a sealing member, and processes each component in order to secure the high bearing performance required as the information equipment becomes more and more high-performance. Efforts have been made to increase the precision and assembly precision. On the other hand, with the tendency of low cost of information equipment, the demand for cost reduction for this kind of fluid bearing device is also becoming more and more strict.

One of the important points in reducing the cost of this type of fluid bearing device is the efficiency of the assembly process. In other words, the housing and the bearing sleeve, the housing and the thrust member, and the housing and the sealing member are usually fixed by using an adhesive, but a relatively long time is required from the application of the adhesive to the solidification, thereby reducing the efficiency of the assembly process. It is the cause. Moreover, the possibility of generation | occurrence | production of outgas by an adhesive agent and deterioration of adhesive force with time is also concerned.

On the other hand, it is possible to eliminate the above-mentioned disadvantages by employing the press fitting as the fixing means, but there is a concern that a reduction in the dimensional accuracy of the component due to the press input or the occurrence of wear powder (particulates) due to the sliding of the components during the press fitting.

An object of the present invention is to reduce the manufacturing cost of the housing in this type of fluid bearing device and to reduce the adhesive of the fixing parts such as the housing and the bearing sleeve, thereby improving the assembly process. Therefore, it is possible to provide a fluid bearing device at a lower cost.

Another object of the present invention is to provide a fluid bearing device with less outgassing from the fixing portions between the parts and deterioration of the holding force over time.

It is still another object of the present invention to provide a fluid bearing device with higher reliability while maintaining dimensional accuracy of parts and suppressing contamination of contaminants into the bearing device.

In order to achieve the above object, the present invention provides a housing, a bearing sleeve disposed inside the housing, a shaft member inserted into the inner circumferential surface of the bearing sleeve, and a radial bearing clearance between the inner circumferential surface of the bearing sleeve and the outer circumferential surface of the shaft member. In a fluid bearing device having a radial bearing portion for non-contacting support of a shaft member in a radial direction by an oil film of lubricating oil, the housing is formed of a resin material, and the bearing sleeve has an action of ultrasonic vibration on the inner circumferential surface of the housing. It provides a configuration that is pressed under and welded under.

Since the housing made of resin can be formed by mold molding such as injection molding, it can be manufactured at a lower cost than the metal housing by machining such as turning, and also secures relatively high precision compared to the metal housing by press working. can do.

The bearing sleeve is pressed into the inner circumferential surface of the housing under the action of ultrasonic vibrations, ie applying ultrasonic vibration to the housing or / and the bearing sleeve. Since the area in contact with the bearing sleeve of the inner circumferential surface of the housing during melting is melted or softened by the action of ultrasonic vibration, the pressure input at the time of pressing is significantly reduced compared to the case of pressing only (when pressing without ultrasonic vibration). Can be reduced. As a result, fluctuations in the outer diameter of the housing and the inner diameter of the bearing sleeve due to the press-in can be suppressed, and good dimensional accuracy can be maintained. In addition, by reducing the pressing force at the time of pressing, the occurrence of wear powder from the sliding portion of the housing and the bearing sleeve is reduced, and contamination of contaminants into the bearing device is suppressed.

The ultrasonic vibration may be continuously applied even after the press fitting operation of the bearing sleeve is completed. Alternatively, when the inner circumferential surface of the housing is melted to the extent that the housing is welded at the completion of the press fitting operation, the ultrasonic vibration is applied at the completion of the press fitting operation. You can stop. In this way, the area in contact with the bearing sleeve of the inner circumferential surface of the housing is melted and welded to the bearing sleeve by the action of ultrasonic vibration (ultrasound welding). The work efficiency can be improved as compared with the fixing by the conventional adhesive, and the outgassing from the fixing part and the aging deterioration of the fixing force can be prevented or suppressed.

The resin forming the housing is not particularly limited as long as it is a thermoplastic resin. However, in the case of amorphous resin, for example, polysulfone (PSF), polyethersulfone (PES), polyphenylsulfone (PPSF) and polyetherimide (PEI) It is available. In the case of crystalline resin, for example, liquid crystal polymer (LCP), polyether ether ketone (PEEK), polybutylene terephthalate (PBT), and polyphenylene sulfide (PPS) can be used. Moreover, you may mix | blend a filler with these resin. Although the kind of filler is not specifically limited, For example, fibrous fillers, such as glass fiber, whisker-like fillers, such as potassium titanate, scaly fillers, such as mica, carbon fiber, carbon black, graphite, a carbon nanomaterial, metal powder, etc. Fibrous or powdery conductive fillers can be used. When mix | blending an electroconductive filler, a carbon nanomaterial is preferable at the point of the high electroconductivity, the favorable dispersibility in a resin matrix, the favorable abrasive resistant property, the low outgas property, etc. As the carbon nanomaterial, carbon nanofibers are preferable. This carbon nanofiber includes what is called "carbon nanotube" whose diameter is 40-50 nm or less.

The shaft member is mounted with a housing, a bearing sleeve disposed inside the housing, a shaft member inserted into the inner circumferential surface of the bearing sleeve, and an oil film of lubricating oil generated in the radial bearing gap between the inner circumferential surface of the bearing sleeve and the outer circumferential surface of the shaft member. In a fluid bearing device having a radial bearing portion for non-contact support in the radial direction and a thrust bearing portion for supporting the shaft member in the thrust direction, the housing is formed of the resin material, and the bearing sleeve and the thrust bearing portion are formed. At least one of the thrust members to be configured may be press-fitted and welded to the inner circumferential surface of the housing under the action of ultrasonic vibration.

In addition, the shaft member is formed by a housing, a bearing sleeve disposed inside the housing, a shaft member inserted into the inner circumferential surface of the bearing sleeve, and an oil film of lubricating oil generated in the radial bearing gap between the inner circumferential surface of the bearing sleeve and the outer circumferential surface of the shaft member. In a fluid bearing device having a radial bearing portion for non-contact support in a radial direction and a sealing portion for sealing the inside of the housing, the housing is formed of the resin material, and the seal is formed of a bearing sleeve and a sealing portion. At least one of the members may be press-welded to the inner circumferential surface of the housing under the action of ultrasonic vibration.

According to the present invention, the manufacturing cost of the housing can be reduced, and the adhesive of the fixing parts such as the housing and the bearing sleeve can be reduced, whereby the assembling process can be made more efficient. Can provide.

Moreover, according to this invention, the fluid bearing apparatus which is excellent in quality and durability with little generation | occurrence | production of outgassing from the fixing part between components, and deterioration of a fixing force with time, can be provided.

Further, according to the present invention, it is possible to provide a more reliable fluid bearing device in which the dimensional accuracy of parts is maintained and contamination of contaminants into the device is suppressed.

1 is a cross-sectional view of a spindle motor for information apparatus incorporating a dynamic bearing apparatus according to an embodiment of the present invention.

2 is a cross-sectional view showing a dynamic pressure bearing device according to an embodiment of the present invention.

FIG. 3 is a view of the housing as viewed from the direction A in FIG. 2.

4: shows the bearing sleeve, FIG. 4 (a) is sectional drawing, FIG. 4 (b) is a figure which shows a lower end surface, and FIG. 4 (c) is a figure which shows an upper end surface.

5 is a cross-sectional view showing a dynamic bearing apparatus according to another embodiment of the present invention.

6 is a cross sectional view showing a housing and a bearing sleeve after press-fitting and welding.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

Fig. 1 conceptually shows an example of the configuration of a spindle motor for information apparatus in which the fluid bearing device (fluid dynamic bearing device) 1 according to this embodiment is assembled. Since the spindle motor is used for a disk drive such as an HDD, a dynamic pressure bearing device 1 for rotatably supporting the shaft member 2 in a non-contact manner, and a rotor (disk hub) mounted on the shaft member 2. (3) and the stator 4 and the rotor magnet 5 which oppose each other with the radial gap therebetween, for example. The stator 4 is installed on the outer circumference of the bracket 6, and the rotor magnet 5 is installed on the inner circumference of the disc hub 3. The housing 7 of the dynamic pressure bearing device 1 is attached to the inner circumference of the bracket 6. In the disk hub 3, one or more disks D, such as a magnetic disk, are held. When the stator 4 is energized, the rotor magnet 5 rotates by the electromagnetic force between the stator 4 and the rotor magnet 5, whereby the disc hub 3 and the shaft member 2 are integrated. To rotate.

2 shows a dynamic pressure bearing device 1. This dynamic pressure bearing apparatus 1 is comprised from the housing 7, the bearing sleeve 8 and the sealing member 9 fixed to the housing 7, and the shaft member 2 as components.

The first radial bearing portion R1 and the second radial bearing portion R2 are axially disposed between the inner circumferential surface 8a of the bearing sleeve 8 and the outer circumferential surface 2a1 of the shaft portion 2a of the shaft member 2. It is installed in isolation. In addition, a first thrust bearing portion T1 is provided between the lower end surface 8c of the bearing sleeve 8 and the upper end surface 2b1 of the flange portion 2b of the shaft member 2, and the housing 7 The second thrust bearing portion T2 is provided between the inner bottom surface 7b1 of the bottom portion 7b and the lower end surface 2b2 of the flange portion 2b. In addition, for convenience of explanation, explanation is given, with the bottom 7b side of the housing 7 as the lower side and the side opposite to the bottom 7b as the upper side.

The housing 7 is formed into a cylindrical shape with a bottom by injection molding a resin material containing 2 to 8 wt% of a carbon nanotube as a conductive filler to a liquid crystal polymer (LCP) as a crystalline resin, for example. 7a and the bottom part 7b integrally formed in the lower end of the side part 7a are provided. As shown in FIG. 3, the spiral-shaped dynamic pressure groove 7b2 is formed in the inner bottom face 7b1 of the bottom part 7b which becomes the thrust bearing surface of the 2nd thrust bearing part T2, for example. This dynamic pressure groove 7b2 is molded at the time of injection molding of the housing 7. That is, the groove mold | membrane which forms the dynamic pressure groove 7b2 is processed in the predetermined | prescribed part (site | part which molds the inner bottom face 7b1) of the shaping | molding die which molds the housing 7, and at the time of injection molding of the housing 7, By transferring the shape of the groove frame to the inner bottom surface 7b1 of the housing 7, the dynamic pressure groove 7b2 can be molded simultaneously with the molding of the housing 7. Further, the stepped portion 7d is integrally formed at a position axially upward from the inner bottom surface (thrust bearing surface) 7b1 by a predetermined dimension x.

The shaft member 2 is formed of a metal material such as stainless steel, for example, and includes a shaft portion 2a and a flange portion 2b integrally or separately provided at the lower end of the shaft portion 2a.

The bearing sleeve 8 is, for example, formed in a cylindrical shape with a porous body made of sintered metal, in particular, a porous body made of copper, and fixed at a predetermined position on the inner circumferential surface 7c of the housing 7.

On the inner circumferential surface 8a of the bearing sleeve 8 formed of this sintered metal, two upper and lower regions serving as radial bearing surfaces of the first radial bearing portion R1 and the second radial bearing portion R2 are axially oriented. The two regions are each formed with herringbone-like dynamic pressure grooves 8a1 and 8a2 as shown in Fig. 4A, respectively. The upper dynamic pressure groove 8a1 is formed axially asymmetrically with respect to the axial center m (axial center of the upper and lower inclined groove regions), and has an axial dimension x1 of the upper region than the axial center m. ) Is larger than the axial dimension X2 of the lower region. In addition, on the outer peripheral surface 8d of the bearing sleeve 8, one or a plurality of axial grooves 8d1 are formed over the entire axial length. In this example, three axial grooves 8d1 are formed at equal intervals in the circumferential direction.

In the lower end surface 8c of the bearing sleeve 8, which becomes the thrust bearing surface of the first thrust bearing portion T1, for example, a spiral-shaped dynamic pressure groove 8c1 as shown in Fig. 4B is formed.

As shown in FIG.4 (c), the upper end surface 8b of the bearing sleeve 8 is the inner diameter side area | region 8b2 and the outer diameter side area | region 8b3 by the circumferential groove 8b1 formed in the substantially central part of the radial direction. ), One or a plurality of radial grooves 8b21 are formed in the inner diameter side region 8b2. In this example, three radial grooves 8b21 are formed at circumferential equal intervals.

The sealing member 9 is fixed to the inner circumference of the upper end of the side portion 7a of the housing 7, for example, and the inner circumferential surface 9a is tapered surface 2a2 formed on the outer circumference of the shaft portion 2a and a predetermined sealing space. Oppose with (S) in between. In addition, the tapered surface 2a2 of the shaft part 2a is gradually reduced toward the upper side (outside with respect to the housing 7), and functions also as a centrifugal force sealing by rotation of the shaft member 2. Moreover, the outer diameter side area | region 9b1 of the lower end surface 9b of the sealing member 9 is formed with the diameter slightly larger than the inner diameter side area | region.

The dynamic pressure bearing apparatus 1 of this embodiment is assembled by the following process, for example.

First, the shaft member 2 is attached to the bearing sleeve 8. And while applying ultrasonic vibration to the housing 7 and / or the bearing sleeve 8, the outer peripheral surface 8d of the bearing sleeve 8 is press-fitted into the inner peripheral surface 7c of the housing 7 with a predetermined fastening margin. When press-fitting, the area in contact with the bearing sleeve 8 of the inner circumferential surface 7c of the housing 7 is melted or softened by the action of ultrasonic vibrations, and thus only by press-fitting (when pushing-in without applying ultrasonic vibrations). On the other hand, the press input at the time of press injection can be reduced significantly. The bearing sleeve 8 is press-fitted to a position where the lower end surface 8c contacts the stepped portion 7d of the housing 7. By contacting the lower end face 8c of the bearing sleeve 8 to the step 7d of the housing 7, the axial position of the bearing sleeve 8 with respect to the housing 7 can be determined accurately. After the press fitting operation of the bearing sleeve 8 is completed, the ultrasonic vibration is applied, or when the inner circumferential surface of the housing 7 is melted to the extent that it can be welded at the completion of the press fitting operation, the application of the ultrasonic vibration is stopped, The outer circumferential surface 8d of the bearing sleeve 8 is welded to the inner circumferential surface 7c of the housing 7 (ultrasonic welding).

6 has shown the cross section of the housing 7 and bearing sleeve 8 after press fitting and welding. The inner peripheral surface 7c of the housing is fixed to the outer peripheral surface 8d of the bearing sleeve 8 by press fitting and welding. Since the bearing sleeve 8 is formed of a porous sintered metal, the molten resin of the inner circumferential surface 7c of the housing 7 is the surface opening (the porous structure of the sintered metal) of the outer circumferential surface 8d of the bearing sleeve 8 during welding. Inside the pores from the opening formed on the surface thereof to solidify. In addition, since the portion solidified in the inner pores firmly adheres to the housing 7 and the bearing sleeve 8 by a kind of anchor effect, relative positional displacement between the two is unlikely to occur. Further, at a position facing the axial groove 8d1 of the bearing sleeve 8, a part of the inner circumferential surface 7c of the housing 7 protrudes in the rib shape in the inner diameter direction, and this rib-shaped portion 7c1 is By engaging the axial groove 8d1 in the rotational direction, the positional shift of the housing 7 and the bearing sleeve 8 in the rotational direction becomes more difficult.

The fastening allowance (initial value) 6 between the inner circumferential surface 7c of the housing 7 and the outer circumferential surface 8d of the bearing sleeve 8 is set to 2δ = 20 to 30 μm, for example. The value of the tightening allowance δ is even when the housing 7 and the bearing sleeve 8 are thermally expanded under the use temperature rise (the resin 7 has a larger thermal expansion than the bearing sleeve 8). Is set as a value in which a tightening margin of about 10 μm is left as a diameter value. In addition, the tightening allowance (initial value) (delta) after a press fit and welding is the whole amount or partial amount of the tightening allowance (initial value) (delta) similarly to the press fit value at the time of a press injection. In addition, since the protrusion amount of the rib-shaped portion 7c1 in the inner diameter direction is approximately equal to the tightening allowance (initial value) δ and is a small amount, the axial groove 8d1 is formed even in the state where the rib-shaped portion 7c1 is formed. The cross sectional area of is maintained in the required amount.

Next, the sealing member 9 is fixed to the inner circumference of the upper end of the side portion 7a of the housing 7 by means similar to, for example, the bearing sleeve 8. In this state, the inner diameter side region of the lower end surface 9b of the sealing member 9 is in contact with the inner diameter side region 8b2 of the upper end surface 8b of the bearing sleeve 8.

When the assembly is completed as described above, the shaft portion 2a of the shaft member 2 is inserted into the inner circumferential surface 8a of the bearing sleeve 8, and the flange portion 2b is the lower end surface 8c of the bearing sleeve 8. ) And a space portion between the inner bottom surface 7b1 of the housing 7. Thereafter, the inner space of the housing 7 sealed by the sealing member 9 includes the internal pores of the bearing sleeve 8 and is filled with lubricating oil. The oil surface of the lubricating oil is maintained within the range of the sealing space S.

When the shaft member 2 is rotated, the regions (two upper and lower regions) which become radial bearing surfaces of the inner circumferential surface 8a of the bearing sleeve 8 are respectively the outer circumferential surface 2a1 and the radial portion of the shaft portion 2a. Oppose the bearing gap between them. In addition, the area | region used as the thrust bearing surface of the lower end surface 8c of the bearing sleeve 8 opposes the upper end surface 2b1 of the flange part 2b, and the thrust bearing clearance gap between them, and the inner bottom face of the housing 7 The area | region used as the thrust bearing surface of 7b1 opposes the lower end surface 2b2 of the flange part 2b, and the thrust bearing clearance gap. Then, as the shaft member 2 rotates, dynamic pressure of lubricating oil is generated in the radial bearing gap, and the shaft portion 2a of the shaft member 2 is formed by an oil film of lubricating oil formed in the radial bearing gap. It is rotatably contactlessly supported in the radial direction. Thereby, the 1st radial bearing part R1 and the 2nd radial bearing part R2 which rotatably support the shaft member 2 rotatably in radial direction are comprised. At the same time, dynamic pressure of lubricating oil is generated in the thrust bearing gap, and the flange portion 2b of the shaft member 2 is rotatably and non-contactably supported in both thrust directions by an oil film of lubricating oil formed in the thrust bearing gap. Thereby, the 1st thrust bearing part T2 and the 2nd thrust bearing part T2 which support the axial member 2 rotatably and non-contactingly in the thrust direction are comprised. The thrust bearing gap (referred to as δ1) of the first thrust bearing part T1 and the thrust bearing gap (referred to as δ2) of the second thrust bearing part T2 are from the inner bottom surface 7b1 of the housing 7. The axial dimension x up to the stepped portion 7d and the axial dimension w of the flange portion 2b of the shaft member 2 can be managed precisely as xw = δ1 + δ2. have.

As mentioned above, the dynamic pressure groove 8a1 of the 1st radial bearing part R1 is formed axially asymmetric with respect to the axial center m, and is an axial direction of an area upper than an axial center m. The dimension X1 is larger than the axial dimension X2 of the lower region (Fig. 4 (a)). Therefore, when the shaft member 2 is rotated, the pulling force (pumping force) of the lubricating oil by the dynamic pressure groove 8a1 becomes larger in the upper region than in the lower region. And by the differential pressure of this pulling force, the lubricating oil filled in the clearance gap between the inner peripheral surface 8a of the bearing sleeve 8 and the outer peripheral surface 2a1 of the shaft part 2a flows downward, and the 1st thrust bearing part T1 Thrust bearing clearance → axial groove 8d1 → outer diameter region 9b1 of lower end surface 9b of sealing member 9 and outer diameter region 8b3 of upper end surface 8b of bearing sleeve 8 Annular gap therebetween → circumferential groove 8b1 of the upper end face 8b of the bearing sleeve 8 circulates a path called radial groove 8b21 of the upper end face 8b of the bearing sleeve 8, It is pulled back into the radial bearing clearance of the radial bearing part R1. In this way, by lubricating oil configured to circulate the inner space of the housing 7, the phenomenon of the pressure of the lubricating oil in the inner space is prevented from being locally negative, so that bubbles are generated and bubbles are generated due to the negative pressure. This can solve problems such as leakage of lubricant and generation of vibration. In addition, even when bubbles are mixed in the lubricant for some reason, when bubbles are circulated along the lubricant, they are discharged from the oil surface (gas-liquid interface) of the lubricant in the sealing space S, so that adverse effects caused by the bubbles are more effectively prevented. do.

5 shows a fluid bearing device 21 according to another embodiment. The fluid bearing device 21 of this embodiment is substantially different from the fluid bearing device 1 shown in FIG. 2 in that the sealing portion 7a is integrally formed in the housing 7. The bottom portion is formed by a separate thrust member 10.

The sealing portion 7a extends integrally from the upper end of the cylindrical side portion 7b to the inner diameter side, and the inner circumferential surface 7a1 has a tapered surface 2a2 provided on the outer circumference of the shaft portion 2a and the predetermined sealing space S. To face each other).

The thrust member 10 is formed of metal material, such as a resin material or brass, for example, and is fixed to the lower end part of the inner peripheral surface of the housing 7. In the end surface 10a of the thrust member 10, the dynamic pressure groove similar to the dynamic pressure groove 7b2 shown in FIG. 3 is formed. In addition, in this embodiment, the thrust member 10 is integrally provided with the annular contact part 10b extended upward from the outer peripheral edge part of the end surface 10a. The upper end surface of the contact portion 10b is in contact with the lower end surface 8c of the bearing sleeve 8, and the inner circumferential surface of the contact portion 10b faces the outer circumferential surface of the flange portion 2b with a gap therebetween.

The fluid bearing device 1 of this embodiment is assembled by the following process, for example.

First, similarly to the above-described embodiment, the outer circumferential surface 8d of the bearing sleeve 8 is prescribed to the inner circumferential surface 7c of the housing 7 while applying ultrasonic vibration to the housing 7 or / and the bearing sleeve 8. Press and weld with a tightening allowance of. The bearing sleeve 8 is press-fitted to the position where the upper end surface 8b contacts the inner side surface 7a2 of the sealing portion 7a. By contacting the upper end surface 8b of the bearing sleeve 8 with the inner surface 7a2 of the seal 7a, the axial position of the bearing sleeve 8 relative to the housing 7 can be accurately determined.

Next, the shaft member 2 is attached to the bearing sleeve 8, and then the thrust member 10 is, for example, by the same means as that of the bearing sleeve 8 of the above-described embodiment. It fixes to the lower end part of the inner peripheral surface 7c. In this state, the upper end surface of the contact portion 10b of the thrust member 10 contacts the lower end surface 8c of the bearing sleeve 8. Thereby, the axial position of the thrust member 10 with respect to the bearing sleeve 8 can be determined correctly. Therefore, by managing the axial dimension of the contact part 10b and the flange part 2b, the thrust bearing clearance of the 1st thrust bearing part T1 and the 2nd thrust bearing part T2 can be set precisely.

When the assembly is completed as described above, the shaft portion 2a of the shaft member 2 is inserted into the inner circumferential surface 8a of the bearing sleeve 8, and the flange portion 2b is the lower end surface 8c of the bearing sleeve 8. ) And the end face 10a of the thrust member 10 are accommodated. Thereafter, the internal space of the housing 7 sealed by the sealing portion 7a includes the internal pores of the bearing sleeve 8 and is filled with lubricating oil. The oil surface of the lubricating oil is maintained in the range of the sealing space S.

Since other matters are based on embodiment mentioned above, overlapping description is abbreviate | omitted.

The present invention is similarly applicable to a fluid bearing device employing a so-called pivot bearing as a thrust bearing portion, and a fluid bearing device employing a so-called cylindrical bearing as a radial bearing portion.

EXAMPLE

Embodiment ("Ultrasonic + Press-In") in which the bearing sleeve 8 is fixed to the inner circumferential surface 7c of the housing 7 in the above-described form, and the bearing sleeve 8 is bonded to the inner circumferential surface 7c of the housing 7 with an adhesive. Shrinkage amount of the inner diameter dimension of the bearing sleeve 8 with respect to the fixed comparative example ("adhesion") and the comparative example ("pressing") which fixed the bearing sleeve 8 to the inner peripheral surface 7c of the housing 7 only by press fitting, The amount of fine particles generated and the pressure input were measured. The results are shown in Tables 1-3.

Fixing method Inner diameter of bearing sleeve Group After fixing Inner diameter shrinkage Ultrasound + Indentation φ3.99577 φ3.99523 0.00054 adhesion φ3.99542 φ3.99487 0.00055 Indentation φ3.99557 φ3.99520 0.00057

Fixing method Particulate count More than 2㎛ More than 3㎛ 5 ㎛ or more 10 ㎛ or more More than 15㎛ Ultrasound + Indentation 10 6 3 One 0 Indentation 12 6 4 3 One adhesion 12 7 3 0 0

Fixing method Pressure input (N) Ultrasound + Indentation 30 Indentation 143

[Shrinkage of Internal Diameter]

As shown in Table 1, the embodiment ("ultrasound + indentation") has a small shrinkage of the inner diameter of the bearing sleeve 8 to the same degree as the comparative example ("gluing"), and satisfactory dimensional accuracy of the bearing sleeve 8. It can be confirmed that is maintained even after fixing.

[Quantity of particulates]

As shown in Table 2, in the case of the comparative example ("ultrasound + indentation"), the fine particles having a large diameter were measured, but the example ("ultrasound + indentation") was a good result similarly to the comparative example ("adhesion"). Indicated.

[Pressure Input]

As shown in Table 3, the Example ("ultrasonic wave + indentation") confirmed that the pressure input can be reduced to about 1/5 compared with the comparative example ("indentation").

Claims (3)

An oil film of lubricating oil generated in the housing, the bearing sleeve disposed inside the housing, the shaft member inserted into the inner circumferential surface of the bearing sleeve, and the radial bearing gap between the inner circumferential surface of the bearing sleeve and the outer circumferential surface of the shaft member. In the fluid bearing device having a radial bearing portion for non-contact support of the shaft member in the radial direction, And the housing is formed of a resin material, and the bearing sleeve is pressed and welded to the inner circumferential surface of the housing under the action of ultrasonic vibration. An oil film of lubricating oil generated in the housing, the bearing sleeve disposed inside the housing, the shaft member inserted into the inner circumferential surface of the bearing sleeve, and the radial bearing gap between the inner circumferential surface of the bearing sleeve and the outer circumferential surface of the shaft member. A fluid bearing device comprising a radial bearing portion for noncontacting the shaft member in a radial direction, and a thrust bearing portion for supporting the shaft member in a thrust direction. The housing is formed of a resin material, and at least one of the bearing sleeve and the thrust member constituting the thrust bearing portion is press-fitted and welded to the inner circumferential surface of the housing under the action of ultrasonic vibration. Device. An oil film of lubricating oil generated in the housing, the bearing sleeve disposed inside the housing, the shaft member inserted into the inner circumferential surface of the bearing sleeve, and the radial bearing gap between the inner circumferential surface of the bearing sleeve and the outer circumferential surface of the shaft member. In the fluid bearing device having a radial bearing portion for non-contacting support of the shaft member in the radial direction, and a sealing portion for sealing the inside of the housing, The housing is formed of a resin material, and at least one of the bearing sleeve and the sealing member constituting the sealing portion is press-fitted and welded to the inner peripheral surface of the housing under the action of ultrasonic vibration. .

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